1. The Field of the Invention
The present invention relates to a wear indicator for a motor carbon brush and to a commutator motor comprising one or more of the wear indicators.
2. The Relevant Technology
A conventional commutator motor includes a housing, a carbon brush which is slidably mounted within the housing and at least one alarm indicator light. An end of the carbon brush bears against an elastic element and the other end contacts the round surface of the commutator. The carbon brush is biased against the commutator by means of the elastic element. A wire is embedded in the carbon brush in order to detect the wear degree to ensure that the carbon brush is timely replaced. When the carbon brush is worn and slides to a predetermined position, the wire is exposed and turns the alarm indicator light on. Generally such a carbon brush with an embedded wire is complicated to manufacture.
Another conventional arrangement incorporates an opening at a predetermined position of the carbon brush. A lighting element is disposed on one side of the carbon brush and a receiving element on the other side. When the carbon brush is worn and slides to a predetermined position, the receiving element receives through the opening the light emitted by the lighting element and turns the alarm indicator light on. A disadvantage of this arrangement is that the opening may become blocked (e.g., by dust) which interrupts the light making the alarm ineffective.